Currently, there are no SAE 6-sized solenoid valves on the market which operate effectively at elevated temperatures above about 250.degree. Fahrenheit and which exert over 6 pounds of force. In the past, it has proved difficult to assemble such solenoids in a way that maintains high efficiency at low current as well as providing a linearized force-stroke curve for increased force at the hydraulic switching point. Moreover, it has been difficult to provide efficient hydraulic switching in very small solenoid valves because the valves tend to stick at the switching point. In order to overcome sticking, the tendency has to been to use more powerful larger valve components which, of course, increases the expense and size of the valves. It is now highly desirable to have replaceable electromechanical assemblies in the automotive industry so that an entire assembly is replaced when a component thereof malfunctions. This is in large part because it is very difficult to determine which miniature component is malfunctioning. Accordingly, there is the need to high reliability in components such as miniature valves and it is important that this high reliability be achieved at a low cost. If the valves are relatively expensive, then the cost of replacement electromechanical assemblies is increased and if the valves are unreliable, then a malfunction in a single valve can result in an entire assembly having to be replaced.
As is clear from patents such as U.S. Pat. No. 4,552,179, assembly of miniature solenoid valves has presented a challenge for many years. Cost effective assembly techniques which accomplish more than one function such as minimizing the flux leakage and providing a linearized stroke curve which can be matched to a return spring curve are not available.